1) Field of the Invention
This invention relates generally to fabrication of a semiconductor device and more particularly to a method and structure for forming a damascene structure with reduced capacitance by using carbon nitride, boron nitride, or boron carbon nitride to form a low-K passivation layer, etch stop layer, and/or cap layer.
2) Description of the Prior Art
As semiconductor dimensions continue to shrink and device density continues to increase, capacitance between conductive structures becomes increasingly important. With a smaller amount of dielectric material separating conductive structures, the dielectric constant must be increased to provide the same capacitance. However, materials for a passivation layer, an etch stop layer, and a cap layer are typically chosen for their etch selectivity properties.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following patents.
U.S. Pat. No. 5,834,845 (Stolmeijer) shows a damascene interconnect method which discloses a BN etch stop layer, but states that a silicon nitride etch stop layer is preferred. This invention does not show a passivation layer or a cap layer, nor does it disclose any method for forming a BN etch stop layer.
U.S. Pat. No. 5,821,169 (Nguyen et al.) shows a dual damascene process with a hard mask (cap layer) material selected from a group of insulating materials including BN. This invention teaches that the hard mask material should be selected for etch selectivity to the inter level dielectric layer, and does not disclose any method for forming a BN hard mask layer.
U.S. Pat. No. 5,904,565 (Nguyen et al.) shows a dual damascene process with various cap, etch stop, and barrier layers.
U.S. Pat. No. 5,708,559 (Brabozon et al.) teaches a damascene capacitor process with a dielectric layer of BN.